Energy storing 3D-printed materials mimic eagle’s grip

Scientists at Queen Mary University of London and University of Cambridge have used 3D printing to create materials that store energy like eagles’ talons as they grip prey.

An auxetic ratcheting building block that could be embedded in new materials (Credit: Stoyan Smoukov)

Known as auxetics, the materials collapse in on themselves when compressed rather than bulging outwards, allowing energy to be stored within the structures. Auxetics have recently been adopted for lightweight armour, the material collapsing upon impact from a bullet and absorbing the kinetic energy. But while the auxetics used for armour tend to have sharp corners that can fracture over multiple impacts, this new category has smoothed curves that allow multiple reuses and deformations. Similar to eagle’s claws as they grip prey, the material ‘locks’ the energy into place and maintains it with minimal effort.

“The exciting future of new materials designs is that they can start replacing devices and robots,” said Queen Mary’s Dr Stoyan Smoukov, principal investigator of the study, which is published in Frontiers in Materials.

“All the smart functionality is embedded in the material, for example the repeated ability to latch onto objects the way eagles latch onto prey, and keep a vice-like grip without spending any more force or effort.”

According to the team, the nature-inspired designs could be used in energy-efficient gripping tools for industry, re-configurable shape-on-demand materials, and lattices with unique thermal expansion behaviour. The research could also lay the foundation for designs of lightweight 3D supports which fold in specific ways and store energy that could be released on demand. Smoukov said the designs were specifically developed so that they could be 3D-printed, providing flexibility that other fabrication processes could not deliver.

“By growing things layer-by-layer from the bottom up, the possible material structures are mostly limited by imagination, and we can easily take advantage of inspirations we get from nature,” he said.